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Numerical Study on Combustion Features of Gasified Biomass Gas
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.ORCID iD: 0000-0003-4115-7330
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

There is a great interest to develop biomass combustion systems for industrial and utility applications. Improved biomass energy conversion systems are designed to provide better combustion efficiencies and environmental friendly conditions, as well as the fuel flexibility options in various applications. The gas derived from the gasification process of biomass is considered as one of the potential candidates to substitute traditional fuels in a combustion process. However, the gascomposition from the gasification process may have a wide range of variation depending on the methods and fuel sources. The better understanding of the combustion features for the Gasified Biomass Gas(GBG) is essential for the development of combustion devices to be operated efficiently and safely at the user-end.

The objective of the current study is therefore aiming to achieve data associated with the combustion features of GBG fuel for improving the efficiency and stability of combustion process. The numerical result is achieved from the kinetic models of premixed combustion with a wide range of operating ranges and variety of gas compositions. The numerical result is compared with experimental data to provide a better understanding of the combustion process for GBG fuel.

In this thesis the laminar flame speed and ignition delay time of the GBG fuel are analyzed, using 1-D premixed flame model and constant volume model respectively. The result from different kinetics are evaluated and compared with experimental data. The influences of initial temperature, pressure and equivalence ratio are considered, as well as the variation of gas compositions. While the general agreement is reached between the numerical result and experimental data for laminarflame speed prediction, deviations are discovered at fuel-rich region and increased initial temperature. For the ignition delay time, deviations are found in the low-temperature and low pressure regime. The empirical equations considering the influence of initial temperature,pressure and equivalence ratio are developed for laminar flame speed and ignition delay times. The influence of major compositions such as CO, H2 and hydrocarbons are discussed in details in the thesis. Furthermore, a simplified kinetic model is developed and optimized based on the evaluation of existing kinetics for GBG fuel combustion. The simplified kinetic model is expected to be used for simulating the complexc ombustion process of GBG fuel in future studies.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , xviii, 51 p.
Series
TRITA-KRV, ISSN 1100-7990 ; 15/04
Keyword [en]
Kinetic model, gasified biomass gas, premixed combustion, laminar flame speed, ignition delay time
National Category
Energy Engineering
Research subject
Biotechnology; Energy Technology
Identifiers
URN: urn:nbn:se:kth:diva-166252ISBN: 978-91-7595-534-6 (print)OAI: oai:DiVA.org:kth-166252DiVA: diva2:810076
Presentation
2015-05-19, Sal M235, Brinellvägen 68, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20150511

Available from: 2015-05-11 Created: 2015-05-06 Last updated: 2015-05-11Bibliographically approved
List of papers
1. Evaluation of reduced kinetics in simulation of gasified biomass gas combustion
Open this publication in new window or tab >>Evaluation of reduced kinetics in simulation of gasified biomass gas combustion
2013 (English)In: ASME Turbo Expo 2013: Turbine Technical Conference and Exposition: Volume 1B: Combustion, Fuels and Emissions, ASME Press, 2013, Vol. 1B, V01BT04A045- p.Conference paper, Published paper (Refereed)
Abstract [en]

It is essentially important to use appropriate chemical kinetic models in the simulation process of gas turbine combustion. To integrate the detailed kinetics into complex combustion simulations has proven to be a computationally expensive task with tens to thousands of elementary reaction steps. It has been suggested that an appropriate simplified kinetics which are computationally efficient could be used instead. Therefore reduced kinetics are often used in CFD simulation of gas turbine combustion. At the same time, simplified kinetics for specific fuels and operation conditions need to be carefully selected to fulfill the accuracy requirements. The applicability of several simplified kinetics for premixed Gasified Biomass Gas (GBG) and air combustion are evaluated in this paper. The current work is motivated by the growing demand of gasified biomass gas (GBG) fueled combustion. Even though simplified kinetic schemes developed for hydrocarbon combustions are published by various researchers, there is little research has been found in literature to evaluate the ability of the simplified chemical kinetics for the GBG combustion. The numerical Simulation tool "CANTERA" is used in the current study for the comparison of both detailed and simplified chemical kinetics. A simulated gas mixture of CO/H2/CH4/CO2/N2 is used for the current evaluation, since the fluctuation of GBG components may have an unpredictable influence on the simulation results. The laminar flame speed has an important influence with flame stability, extinction limits and turbulent flame speed, here it is chosen as an indicator for validation. The simulation results are compared with the experimental data from the previous study [1] which is done by our colleagues. Water vapour which has shown a dilution effect in the experimental study are also put into concern for further validation. As the results indicate, the reduced kinetics which are developed for hydrocarbon or hydrogen combustion need to be highly optimized before using them for GBG combustion. Further optimization of the reduced kinetics is done for GBG and moderate results are achieved using the optimized kinetics compared with the detailed combustion kinetics.

Place, publisher, year, edition, pages
ASME Press, 2013
Keyword
Chemical kinetic model, Combustion simulations, Computationally efficient, Gas-turbine combustion, Hydrocarbon combustion, Hydrogen combustion, Operation conditions, Turbulent flame speed
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-166249 (URN)10.1115/GT2013-95565 (DOI)2-s2.0-84890180038 (Scopus ID)978-079185511-9 (ISBN)
Conference
ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT 2013, San Antonio, Tx, United States, 3 June 2013 through 7 June 2013
Note

QC 20150511

Available from: 2015-05-06 Created: 2015-05-06 Last updated: 2015-06-03Bibliographically approved
2. Kinetic Evaluation of the Laminar Flame Speed for Biomass Derived Gas Combustion
Open this publication in new window or tab >>Kinetic Evaluation of the Laminar Flame Speed for Biomass Derived Gas Combustion
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The gas composition derived from gasification of biomass has been used in gasturbine combustion to achieve higher energy efficiency. However, there is an essential requirement to better understand the combustion characteristics of biomass derived gas before it can be used in the existing combustion facilities. A quantified study of the laminar flame speed of biomass derived gas combustionis presented in this paper. The study was carried out based on the kinetic model of the biomass derived gas flame and the results are compared with the experimental data from the our laboratory and various literatures. The laminarflame speed of the biomass derived gas was evaluated through a range of initial temperature (298 K - 398 K) and pressure (1 atm - 10 atm), as well as with various gas compositions. An empirical relationship for estimating the laminarflame speed has been derived for a composition of typical biomass derived gas. Furthermore, the evaluation of laminar flame speeds with various compositions have been carried out through numerical calculations and results were compared with experimental data from previous studies. The hydrogen concentration in gas composition has shown an essential importance for the laminarflame speed variation.

National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-166250 (URN)
Note

QS 2015

Available from: 2015-05-06 Created: 2015-05-06 Last updated: 2015-05-11Bibliographically approved
3. Kinetic Study on Ignition Delay Time of Biomass Derived Gas Combustion
Open this publication in new window or tab >>Kinetic Study on Ignition Delay Time of Biomass Derived Gas Combustion
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The ignition delay time is one of the fundamental characteristics of a combustionprocess and has an essential effect on the performance of the combustion process. In the current study, a kinetic study on auto iginition delaytime is carried out for biomass derived gas combustion. A gas mixture of CO/H2/CO2/CH4/N2 is used to represent the typical composition from a biomass gasification process. The gas mixture is mixed with air under a certain range of operating conditions. A pressure range from 1 – 32 atm and an initial temperature range from 900 K to 1250 K were considered in the current study.The correlation between the ignition delay time and the operating conditions (pressures, initial temperatures and equivalence ratio) was derived for the biomass derived gas based on the kinetic calculations and published experimental data. The empirical correlation was obtained for the gas mixture ofCO/H2/CO2/CH4/N2/air and the gas mixture of CO/H2/O2/Ar. The influence of fuel compositions of the ignition delay time has also been discussed within this study. However, the influence of composition variation shown in the current study was not significant and was difficult to be cross-validated by various experimental data.

Keyword
Kinetic study, Biomass derived gas, Autoignition delay time
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-166251 (URN)
Note

QS 2015

Available from: 2015-05-06 Created: 2015-05-06 Last updated: 2015-05-11Bibliographically approved

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